say, brian, is at this point, kind of an hour into the event, we still have to accept that the information is going to be incredibly fragmentary and a lot of it's going to be wrong. all of the boston city police department, the federal government, mostly the fbi, the department of homeland security, the white house, everyone is now scrambling to understand what exactly happened in that location. and away from boston, people are starting to put in place some of the preventative security measures that chuck todd just mentioned at the white house. so i expect that we'll start to see some additional police presence in cities like new york, los angeles, chicago. my initial take right now, this could turn out to be anything. but it's a heck of a coincidence to happen right at the end of the boston marathon route. certainly no one in the u.s. government is saying authoritatively what caused this, terrorism or something else. a natural gas explosion.